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  • XMC: Express Micro Controller 2-way RISC VLIW
  • Transcript

    • 1. Network Processors Harsh Chilwal
    • 2. 900MHz Voice 1G 900MHz 1800MHz Voice 2G 900-1800-1900MHz Smart Phone Full web service 3G 900-1800MHz Voice Tiny Internet 2.5G 12 kb/s 170 1000 Data Rate Evolution : Cellular phone generation
    • 3. Evolution : 3G cellular phones base station (BS) mobile station (MS) base station controller (BSC) 12Kb/second 5Mb/second 100Mb/second Network 100 MS 10 BS
    • 4. base station (BS) mobile station (MS) base station controller (BSC) 1Mb/second 500Mb/second 50Gbit/second Network Evolution : 3G cellular phones 500 MS 100 BS NP NP NP
    • 5. 0.1 1 1000 1980 1990 1995 1985 2000 DS0 Year Bandwidth (Mb/s) 64K 1.5M DS1 10 100 DS3 44Mb OC12 622Mb x24 x28 x12 10Gb x16 10,000 OC192 100,000 x4 OC768 40Gb 2005 Evolution : Networks NP DS= Digital signal OC = Optical carrier
    • 6. Networking Trends
      • Increasing Networking Traffic.
      • New sophisticated protocols are being introduced at rapid pace.
      • Need for supporting new applications to provide new services.
      • Convergence of voice and data networks introducing a lot of changes in the communication industry.
      • Increasing TTM Pressures
      • Decreasing product life cycles.
    • 7. General Purpose Processor based Software Router
      • Benefits
      • Flexible for upgrading the system
      • Easy for supporting additional interfaces
      • Quick to develop new products with short TTM.
      • The core processor performs all the routing functionalities
      • Drawbacks
      • Not able to scale up for higher bandwidths, maximum up to OC-12 speeds only
      • Can support complex network operations viz., traffic engineering, QoS, etc
      • with a major reduction in performance
    • 8. ASIC based Routers
      • » Benefits
      • Provide wire-speed performances
      • provided high speed
      • » Drawbacks
      • Lacks flexibility; difficult to meet changing market needs/demands
      • Long design cycles increases TTM reduces PLC.
      • Change in design or failure in design involves more risks
      • Need to replace the ASIC to provide new functionality
      • Complex network operation are still executed in software
    • 9. Network Processor based boxes
      • Promises to provide performance and flexibility
      • Comprises of many packet processing elements supporting multiple threads
      • Achieves higher performance by pipelining and parallel processing both in terms of threads and packet processing elements
      • Brings-in flexibility by due software programming
      • Easy to add features
    • 10. Network Processor
    • 11. Basic Architecture of Network Processors
    • 12. Basic architecture (contd.) Dispatcher Merger CP2 CP1 CP3 CP4 Look-A-Side Co-processors Risc Com – Engine Multiple Streams
    • 13. Intro: Systems and Protocols: Relation with Standards
      • IETF / Forces WG:
        • Data / Forwarding Plane
        • Control Plane
      • NPF:
        • Service Layer
          • System Wide
          • No awareness where things are
        • Functional Layer
          • Awareness where things are
        • Operational Layer
          • Interface Management
      • ITU-T/ANSI/ATM Forum:
        • ATM
      • IEEE
        • Ethernet
      • IETF/Protocols
        • IPv4
        • MPLS
        • PPP/L2TP
        • IPv6
        • MIBs
      Protocols Systems
    • 14. OSI Network Architecture DATA Application Pre. Session Transport Network Data Link Physical 7 6 5 4 3 2 1 DATA AH DATA PH DATA SH DATA TH DATA NH DATA DH DATA PH Application Pre. Session Transport Network Data Link Physical 7 6 5 4 3 2 1 Network Network A B
    • 15. Typical Applications
      • WAN/LAN Switching and Routing, Multi-service Switches, Multi-layer switches, Aggregators
      • Web caching, Load balancing, Web switching, Content based load balancers
      • QoS solutions
      • VoIP Gateways
      • 2.5G and 3G wireless infrastructure equipments
      • Security - Firewall, VPN, Encryption, Access control
      • Storage solutions
      • Residential Gateways
    • 16. Software Framework
    • 17. Scene setting - why specs are not enough
      • 2 NPU vendors want to promote their solution with some ‘numbers’
      • Both chip architectures comprise
        • RISC engines
        • Hardware support engines
        • Various types of interfaces
        • Support for internal and external memory
      • They report the following data
        • Aggregate MIPS
        • Max number of lookups per second
        • ...
      Commonalties in building blocks Commonalties in specifications Commonalties in Interpretation?
    • 18. Specifications
    • 19. Test scenario
      • What is measured? Performance in packets per second versus a forwarding information base (FIB) that is increased in size.
      • Start application is IPv4.
      • Next, counters are added for per flow billing purposes.
      • Next, load balancing is introduced as an additional feature.
      • Finally, encryption becomes an additional requirement for 2% of the data that is being forwarded
    • 20. Performance curves 10 20 30 50 100 150 FIB (K entries) Performance (Mpps) NPU B NPU A IPv4
    • 21. Performance curves 10 20 30 50 100 150 FIB (K entries) Performance (Mpps) NPU B NPU A IPv4 + counters Requires more memory references
    • 22. Performance curves 10 20 30 50 100 150 FIB (K entries) Performance (Mpps) NPU B NPU A IPv4 + counters + Load balancing Requires even more memory references
    • 23. Performance curves 10 20 30 50 100 150 FIB (K entries) Performance (Mpps) NPU B NPU A IPv4 + counters + Load balancing + encryption No extra references and resources available A does not have sufficient resources
    • 24. Architecture A Key extract LU Count Int. mem 3 MIPS cores Int. mem Int. mem External Buffer Mem Sched OC-192 POS OC-192 POS Hash IPv4 + counters + LB + crypto
    • 25. Architecture B IPv4 + counters + LB + crypto LB 10 MIPS cores External Buffer Mem 10GE 10GE Memory interface IMEM
    • 26. Specifications - revisited
    • 27. So
      • No clear value statement could be made in favor of either NPU solutions
        • NPU A achieves higher throughput but with limited flexibility
        • NPU B achieves lower throughput but is more flexible
      • Were the provided specs accurate?
        • Yes.
        • The devices performed up to spec.
        • Although NPU B looks better on paper at first sight, more resources have to be consumed for less per formant results.
        • There is a cost associated with flexibility
      • Were the provided specs relevant?
        • No. They represent granular maximum performances.
        • For ‘real world’ applications,
          • some resources could not be maximally consumed
          • some resources were over consumed
    • 28. Benchmarking considerations
      • Processor core metrics are not always relevant for networking applications
        • It might be relevant for NPU B, since functionality relies almost totally on those cores.
        • It is definitely not the case for NPU A, since there is extensive additional hardware support for specific functions.
      GRANULARITY Highly granular specifications, data or benchmarking information can offer a wrongful picture of the actual performance capabilities of the DUT. Since Network Processing Devices are designed with specific applications in mind, benchmarks must exist for those specific applications
    • 29. Benchmarking considerations
      • External factors affect NPD performance (where you don’t always suspect it)
        • A forwarding application relies on FIB lookups to determine the destination of a packet
        • The size of the FIB table can influence performance in many ways
          • Usage of multiple memory banks
          • increasing number of hash collisions
      EXTERNAL FACTORS Benchmarks should include parameters that take into account external factors that are relevant to the particular applications that are being benchmarked.
    • 30. Benchmarking considerations
      • Interfaces present performance boundary conditions
        • Ethernet applications require inter frame gaps that result in more relaxed pps numbers
      INTERFACES Benchmarks should also specify the types of interfaces that are being used since those interfaces have an impact all by themselves on maximum performance figures
    • 31. Benchmarking considerations
      • Combinations of applications or minor extensions have a completely different impact on both network processing devices
        • NPU A has a lot of well engineered hardware support that can offer additional services BUT fails almost completely when additional computing resources are required
        • NPU B is very ‘soft’; performance degrades slowly when additional services are requested and shows no abrupt peaks in the performance curves.
      HEADROOM Benchmarks should combine applications as they occur in the real world to give a ‘sense’ of headroom that is available to support real world scenarios. It is however very hard to define a metric for headroom
    • 32. CommBench – A Telecommunication Benchmark For NPs CommBench HPAs PPAs
      • RTR
      • FRAG
      • DRR
      • TCP
      • CAST
      • ZIP
      • REED
      • JPEG
    • 33. Benchmark Characteristics – Code & Computational Kernel Sizes
    • 34. Benchmark Characteristics – Computational Complexity N a,l – Num Of Instructions/byte required for app a operationg on a packet of length l
    • 35. Benchmark Characteristics – Instruction Set Characteristics
    • 36. Benchmark Characteristics – Memory Hierarchy
    • 37. Example System: Cisco Toaster 10000
      • Almost all data plane operations execute on the programmable XMC
      • Pipeline stages are assigned tasks – e.g. classification, routing, firewall, MPLS
        • Classic SW load balancing problem
      • External SDRAM shared by common pipe stages
    • 38. Example System: IXP 2400
      • XScale core replaces StrongARM
      • Microengines
        • Faster
        • More: 2 clusters of 4 microengines each
      • Local memory
      • Next neighbor routes added between microengines
      • Hardware to accelerate CRC operations and Random number generation
      • 16 entry CAM
      ME0 ME1 ME2 ME3 ME4 ME5 ME6 ME7 Scratch /Hash /CSR MSF Unit DDR DRAM controller XScale Core QDR SRAM controller PCI
    • 39. References
      • Network Processor Design – Patrick Crowley etal.
      • CommBench - A Telecommunications Benchmark for Network Processors , Tilman Wolf and Mark Franklin. Proceedings of IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS),
      • Network Processing Forum - Benchmarking
      • www. wipro .com/ pdf _files/ networkprocessors _ wipro _ solPPT . pdf
      • http :// intrage . insatlse . fr /~ etienne / netpro . ppt